This invention relates to the utilization of track barcode systems to provide marking and identification for each and every section of a railroad track. The barcodes consisting of each and every unique barcode provide accurate and fixed reference points or coordinates of the track for monitoring, repairing and replacement of railroad track sections. Other railroad properties such as rail types, railroad ties and etc. could also be coded into the barcodes for associated railroad management purposes.
Railroad tracks are consistently monitored by using sensors based on optical, capacitive, eddy current measurements and other mechanisms throughout their lifespan of service. The track gauge between the two paralleled rails and individual rail profile are examples of the parameters that need to be measured and monitored closely for the safety of train operation. Based on modern sensor and automation technologies, the track gauge and rail profile can be measured automatically and accurately at any specific point of the track. In order to calculate rail profile wear or track gauge variation over time, however, it is critical to have accurate and fixed track location identifications for each and every measurement made. Without accurate location repeatability, individual track gauge and rail profile measurements are not very useful no matter how accurate they are.
One of the track section identification methods is to use the existing global positioning system (GPS). However, the current GPS system can only provide location accuracy up to a few meters, which is not accurate enough for the purpose of monitoring track wear. Besides, geographical environment around the monitored tracks, such as underground tunnels, surrounding mountains and nearby tracks, may affect the performance or accuracy of the GPS system as well. In order to calculate the amount of track wear between two measurements taken at two different times, for example, it is necessary to overlap the two rail profiles using a common track location coordinate. Without accurate location identifications, it is impossible to calculate the track wear accurately, even though both individual rail profiles are accurate themselves.
Another track positioning method is to use the existing posts or marks that are located beside and along the railroad tracks. However, it is a very challenging task for a measuring vehicle to detect those posts or marks automatically, since those posts or marks share no standard relative position against the tracks or standard appearance. Manual identification of those reference posts was occasionally adopted, and the location triggers were inputted to a measurement system manually. However, the accuracy and repeatability of manual triggers were not satisfactory due to inevitable human error in this manual operation.
Yet another track positioning method is to use RFID (radio frequency identification) chips and a corresponding chip detector. Since RFID technology is based on radio frequency technology and radio signal could be detected from all directions, the corresponding positioning accuracy is a distance of plus or minus a few feet. Another disadvantage of RFID technology is the high costs associated with a vast amount of RFID chips that should be positioned along the track with a predetermined spacing.
The method of the present invention is to use a track barcode system including an array of pre-coded barcodes and one or more scanners to provide accurate, repeatable and unique track location identifications that could be used by any railroad track management systems. Barcode technologies have been established and are widely used in daily life applications such as library computers, supermarket check-outs and on automated production lines. Outdoor weather-proof barcode sticks were used on the vehicle identification plates which could stay as long as the life of the vehicle. One dimensional and two dimensional barcodes are available. Those barcodes are much more affordable than RFID chips. The corresponding high speed barcode scanners which are capable to carry out thousands of scans per second are also readily available. The trigger signals and the readings generated by the barcode scanners could be transmitted into any existing track measurement systems. Those triggers and location identifications are the important data that could provide the common yet repeatable track coordinates to synchronize different track measurement systems based on a single moving vehicle or different vehicles.
Depending on the size and the orientation of the barcodes, the scan rate of the scanner and the speed of the moving vehicle carrying the scanner, the position accuracy resulted from the method of the present invention could be in a range of a few centimeters or even better. Although this barcode application for railroad track management systems is novel, the barcode technology adopted in the method of the present invention is a solid and proved one. The implementation of a track barcode system for railroad management systems, such as the existing track gauge and rail profiling measurement systems, is economic yet practical.